Gears are used in many mechanical applications including motor vehicles. The gear's teeth are critical areas, subject to the most wear as well as having the greatest propensity to fracture or otherwise fail. It is important that gears are designed to appropriate specifications to avoid such failure, including material size and material quality specifications.
One specific material quality important to wear and strength of the gear teeth is hardness. Each gear material has a usual hardness factor, but this may be changed by additional treatment of the material, either locally (i.e. to wear surfaces) or throughout the gear. The usual hardness or the amended hardness of the gear is often tested for accuracy and consistency. A number of hardness tests and apparatus have been developed, most involving the concept of applying multiple loads at a common position using a device that creates a small depression on the material surface. The difference in indentation depth between a minor load applied and a major load applied is reflective of material hardness.
The gear or other workpiece must be placed in a stable position that allows the indenting portion of a testing device to access the desired area, and to apply the load repeatedly. The gear or other workpiece must be held so as not to be moved by the application of the minor or major load. U.S. Pat. No. 2,712,754 illustrates a typical fixture used to hold a gear or gear-like object in a position for access by a hardness testing device. Specifically, two wedges engage teeth on generally opposite sides of the gear for support. However, fine adjustments are made using a slidable supporting foot and the degree of adjustment is limited.
What is desired is a gear holding fixture that allows for easy adjustment of the position of the gear, thus, allowing hardness testing to be carried out.